Fuel injection nozzles

ABSTRACT

A fuel injection nozzle comprising a supply orifice through which fuel flows to a combustion space of an associated engine a resiliently loaded valve member which co-operates with a seating to prevent the flow of fuel through the supply orifice until the pressure of fuel applied to the valve member from an inlet attains a sufficiently high value, the mechanical connection between the valve member and the resilient means which loads the valve member being divided to define a variable volume chamber. Fuel is supplied to the chamber from the inlet and means is provided to limit the maximum volume of the chamber the arrangement being that fuel flowing through the inlet initially flows at a restricted rate through the supply orifice and when said chamber has attained its maximum volume the valve member is lifted to allow substantially unrestricted flow through the supply orifice.

United States Patent 51 June 13, 1972 Knight [54] FUEL INJECTION NOZZLES [72] inventor: Basil Edward Knight, Pinner, England [73] Assignee: C.A.V. Limited, Birmingham, England [22] Filed: July 7, 1970 [2]] Appl. No.: 52,908

30 Foreign Application Priorit Data July 7, 1969 Great Britain ..34,l32/69 [5i] ..B05b 1/30 [58] Field of Search ..239/88, 92, 533, 89, 90, 91, 239/452 [56] References Cited UNITED STATES PATENTS 3,409,226 I 1/1968 Steiger ..239/533 X 3,464,627 9/1969 Huber ..239/533 X Primary Examiner-M. Henson Wood, Jr. Assistant Examinerdwin D. Grant Anomey-Holman & Stern ABSTRACT A fuel injection nozzle comprising a supply orifice through which fuel flows to a combustion space of an associated engine a resiliently loaded valve member which co-operates with a seating to prevent the flow of fuel through the supply orifice until the pressure of fuel applied to the valve member from an inlet attains a sufficiently high value. the mechanical connection between the valve member and the resilient means which loads the valve member being divided to define a variable volume chamber. Fuel is supplied to the chamber from the inlet and means is provided to limit the maximum volume of the chamber the arrangement being that fuel flowing through the inlet initially flows at a restricted rate through the supply orifice and when said chamber has attained its maximum volume the valve member is lifted to allow substantially unrestricted fiow through the supply orifice.

15 Claims, 3 Drawing Figures PATENTEDJUH13 I572 3, 669 360 SHEET 1 or 3 FIG. I

INVENTOR O NEYS PATENTEDJummz 3,669,860

SHEET 2 or 3 A 54 y 50 14 %/z& '3 7 ---\5' lo I 6 l4 FIG. 6.

\H) INVENTOR [ATTORNEYS FUEL INJECTION NOZZLES This invention relates to fuel injection nozzles of the kind comprising a supply orifice through which fuel flows to a combustion space of an associated engine and a resiliently loaded valve member which co-operates with a seating to prevent the flow of fuel through the supply orifice until the pressure of fuel applied to the valve member from an inlet attains a sufiiciently high value to lift the valve member off the seating.

The object of the invention is to provide such a nozzle in a form in which the initial flow of fuel through the orifice is at a restricted rate.

According to the invention in a nozzle of the kind specified the mechanical connection between the valve member and the resilient means load'mg the valve member is divided to define a variable volume chamber to which fuel is supplied from the inlet, means being provided to limit the maximum volume of the chamber and the arrangement being such that fuel flowing through the inlet initially flows at a restricted rate through the supply orifice and when said chamber has attained its maximum volume the valve member is lifted to allow substantially unrestricted flow through the supply orifice.

In the accompanying drawings:

FIG. 1 is a sectional side elevation of one example of a fuel injection nozzle unit in accordance with the invention,

FIG. 2 is a view similar to FIG. 1 showing a first modification, and

FIG. 3 is a view similar to FIG. 1 showing a second modification.

Referring to FIG. 1 of the drawings there is provided a nozzle head which is mounted at the end of a nozzle body 9. The free end of the nozzle head projects into or forms part of the wall of a combustion space of an associated engine and formed in the free end of the nozzle head is a pair of orifices ll through which in use, liquid fuel under pressure flows into the combustion space of the engine.

Formed within the nozzle head is a bore 12 the blind end of which communicates with a fuel gallery 13 and from which extends-a narrow passage communicating with the orifices 11. About this narrow passage is formed a seating 14 with which co-operates a valve member 15 slidable in the bore 12. It will be noted that the portion of the valve member which cooperates with the seating is of reduced diameter, as compared with the diameter of the bore 12.

Slidable within the bore 12 is piston member 16 which projects out of the bore 12 and carries at its free end, an abutment 17 for a coiled compression spring 18. At its other end the piston member 16 has a truncated conical projection 19 which can partly enter a recess 20 formed in the valve member 15 but which in the absence of fuel under pressure maintains a space between the piston member and the valve member. This space defines a chamber to which liquid fuel under pressure can be supplied by way of a groove 21 formed in the piston member 16 and which communicates with a circumferential groove 22 also formed in the piston member.

In the rest position of the nozzle the groove 22 communicates with a port 23 formed in the nozzle head and this port communicates by way of a restrictor 24, with a fuel inletin the form of an annular groove 25. The fuel gallery 13 is also in communication with the groove 25 which in use, communicates with the outlet of a fuel pump 8.

When fuel under pressure is delivered by the fuel pump the same fuel pressure appears in the gallery 13 and in the chamber and the first effect is to lift the piston member 16 against the action of the spring. The fiow of fuel into the chamber results in a pressure drop across the restrictor 24 with the result that the higher fuel pressure acting upon the end of the valve member 15 lifts the member slightly from the seating 14 to allow fuel flow at a restricted rate through the orifices 1 1. Fuel continues to flow into the chamber so that the piston member 16 continues its movement against the action of the spring 18. The relative movement of the piston member and valve member ceases when the groove 22 is closed to the port 23 and thereafter the piston member and valve member move together under the action of the fuel pressure in the gallery 13 against the action of the spring 18 so that fuel can flow through the orifices 11 at a substantially unrestricted rate.

When the fuel flow from the pump ceases the fuel in the chamber escapes by way of the grooves 21, 22 through a further port 26 to the inlet 25 past a return valve 27, and the piston member moves into contact with the valve member which is then urged onto the seat 14.

If desired and in order to make the nozzle described effective at high speeds the restrictor 24 can be made variable in accordance with speed the degree of restriction reducing with increasing speed.

In the arrangement shown in FIG. 2 identical reference numerals are used for parts having the same function as those parts in FIG. 1. In the arrangement of FIG. 2 the bore 120 is of stepped form, the narrower portion of the bore accommodating the valve member 15 and the wider portion of the bore accommodating acylindrical distance member 28 as well as the piston member 16. The piston member 16 is provided with a projection 30 for abutment with the distance member 28 to define the aforesaid chamber and the space at the stepped end of the wider portion of the bore 12a communicates with a drain passage 29.

In use, fuel under pressure is supplied to the chamber by way of the restrictor 24 from a pump and directly to the chamber 13 from the pump. Initially the piston member 16 is lifted against the action of the spring 18 and as in the previous example, the valve member 15 and distance member 28 then rise to allow fuel at a restricted rate to flow through the orofices 11. During the lifting of the distance member and the valve member fuel fiows into the space defined between the step in the bore 120 and the distance member 28. At a predetermined point in its travel against the action of the spring 18 the piston memberopens a port 31 which opens into the drain passage 29.

The drain passage 29 communicates with a shut-off valve 32 which includes a spring loaded piston 33 which is exposed to the pressure existing in the drain passage 29 and which is movable by an increase in this pressure against the action of a spring 34, to a position in which it substantially prevents flow through the passage'25. When the port 31 isopened fuel pressure is applied to the piston 33 which moves to restrict the size of the passage 25 so that effectively the chamber between the piston member 16 and the distance member 28, is blocked off. Thereafter the valve member 15 rises-under the action of fuel under pressure in the gallery 13 to allow substantially unrestricted flow of fuel through the orifices 11. When the supply of fuel under pressure from the pump ceases the parts return to the rest position under the action of the springs 18. The piston 33 is provided with a restricted opening therethrough so that it can return under the action of the spring 34, during the period between injections. I

In the arrangement shown in FIG. 3 the valve member 50 is of stepped form and its outer and larger end is exposed to a low drain pressure. The gallery 13 is connected to the inlet 25 by way of a restriction 51 and the mechanical connection between the valve member 50 and the spring 18 comprises a pair of cylindrical members 52, 53 of identical diameters slidable within a cylinder 54. Intermediate its end the cylinder is provided with an enlargement 56 which communicates directly with the inlet 25 and the enlargement corresponds with the division between the members 52, 53. The members 52, 53 are spaced by means of a projection on the member 52 and this member is also provided with a circumferential groove 55 intermediate its ends. The groove 55 at a predetermined position of the member 52, places the chamber 13 in direct communication with the inlet 25.

In use, when fuel under pressure is supplied to the inlet 25 the valve member 50 initially lifts to permit flow of fuel at a restricted rate through the orifice 11. This flow of fuel however produces a pressure drop across the restrictor 51 so that the valve member does not lift fully. The fuel pressure within the enlargement 56 however moves the cylindrical member 52 against the action of the spring 18 and at a predetermined position the groove 55 places the gallery 13 in direct communication with the inlet 25. When this occurs the valve member 50 is lifted fully by the fuel pressure in the gallery 13 to allow fuel to flow to the engine at a substantially unrestricted rate. When the flow of fuel ceases the parts return to their rest positions under the action of the spring 18. The extent of movement of the member 52 can be limited by a stop 57.

If desired there may be disposed in the passage between the inlet 25 and the chamber 56 a non-return valve 58 incorporating a restricted passage in its valve member. The provision of this valve has substantially no effect during the supply of fuel through the passage 25. However, when thesupply of fuel under pressure ceases the valve 58 closes and the stored fuel in the chamber can only escape at a restricted rate. In this manner the closure of the valve member 50 onto the seating 14 is assured and the risk of the stored fuel being injected into the engine is minimized.

Various modifications can be made to the system shown in FIG. 3 to obtain different delivery curves. In a first modification the restriction imposed by the restrictor 51 can be made to vary in accordance with the fuel stored in the enlargement 56 and in a second modification it can be made to vary in accordance with the pressure drop developed across it. In a third modification with the restrictor 51 variable as a function of the amount of fuel stored under the spring, i.e. in the enlargement 56 the groove 55 can be profiled to constitute a variable throttle and in a fourth modification which is a variant of the third modification a further restrictor may be placed between the enlargement 56 and the inlet 25. This restrictor may be fixed or variable in accordance with the pressure ,drop developed across it.

I claim:

1. A fuel injection nozzle of the kind comprising a nozzle head, a supply orifice formed in the nozzle head and through which fuel flows to a combustion space of an internal combustion engine, a bore formed in the head, said bore at one end thereof communicating with said orifice, a seating defined at said end of the bore, a valve member slidable within said bore and shaped for co-operation with said seating to prevent fuel flow through said orifice, resilient means for urging the valve member into contact with the seating, a a fuel inlet, passage means through which fuel under pressure from the inlet can be applied to said valve member to lift the valve member from the seating against the action of the resilient means to permit fuel flow through the orifice, means disposed intermediate the valve member and the resilient means, said means defining a variable volume chamber to which fuel is supplied from said inlet, means for limiting the maximum volume of the chamber, a restricted orifice through which fuel flows to said chamber from the inlet, the arrangement being such that fuel flowing through the inlet into the chamber flows at a restricted rate through the restricted orifice so that the pressure within the chamber is lower than that applied tothe valve member, said fuel acting to increase the volume of the chamber by movement of the means disposed between the valve member and the resilient means against the action of the resilient means, said valve member because of the differing pressures applied thereto lifting slightly from the seating to allow restricted flow of fuel through said supply orifice, and when said chamber has attained its maximum volume the valve member being lifted completely from the seating to allow substantially unrestricted flow through the supply orifice.

2. A fuel injection nozzle as claimed in claim 1 in which the means for limiting the maximum volume of the chamber comprises a valve operable to cut off the supply of fuel to the chamber.

3. A fuel injection nozzle as claimed in claim 2 including a groove formed on the means disposed between the valve member and resilient means, said groove communicating with said chamber, and a port formed in the wall of the cylinder in which the piston member is located, said port communicating with said inlet by way of the restricted orifice. the arrangement being that when the piston member has moved a predetermined distance the groove will move out of register with the port and the volume of the chamber will be limited.

4. A fuel injection nozzle as claimed in claim 3 including a non return valve through which said groove communicates with the inlet, said non return valve opening when the supply of fuel through the inlet ceases, to permit fuel to escape from said chamber.

5. A fuel injection noule as claimed in claim 4 in which the degree of restriction offered by said restricted orifice is made to increase as the speed of operation of the associated engine increases.

6. A fuel injection nozzle as claimed in claim 2 in which said means disposed between the valve member and resilient means comprises a piston member and a distance piece disposed between the piston member and valve member, the chamber being defined between the piston member and distance piece and a port formed in the wall of the bore in which the piston member is located, said port being opened to the chamber when the piston member has moved a predetermined amount, and the port communicating with one end of a cylinder containing a spring loaded valve element, the port when opened allowing fuel under pressure to be applied to said valve element to move it againstthe action of its spring, the valve element when so moved, cutting off the supply of fuel from the inlet to the chamber.

7. A fuel injection nozzle as claimed in claim 6 in which the valve element is provided with a restricted opening and through which fuel can flow to a drain from said chamber when the supply of fuel under pressure ceases.

8. A fuel injection nozzle of the kind comprising a nozzle head, a supply orifice formed in the nozzle head and through which fuel flows to a combustion space of an internal combustion engine, a bore formed in the head, said bore at one end thereof communicating with said orifice, a seating defined at said end of the bore, a valve member slidable within said bore and shaped for co-operation with said seating to prevent fuel flow through said orifice, resilient means for urging the valve member into contact with the seating, a fuel inlet, passage means through which fuel under pressure from the inlet can be applied to said valve member to lift the valve member from the seating against the action of the resilient means to permit fuel flow through the orifice, a pair of cylindrical members, disposed intermediate the valve member and the resilient means, a chamber being defined between the cylindrical members, and the chamber being in constant communication with the inlet, a restricted orifice through which fuel flows to said supply orifice at a restricted rate, and a bypass passage through which fuel can flow to said supply orifice at a substantially unrestricted rate when the chamber has attained its maximum volume.

9. A fuel injection nozzle as claimed in claim 8 including a stop to limit the extent of movement of the one cylindrical member adjacent the resilient means against the action of the resilient means.

10. A fuel injection nozzle as claimed in claim 9 in which said by-pass passage is controlled by said one cylindrical member, said member having a groove formed thereon and which registers with a pair of ports to complete said by-pass passage.

11. A fuel injection nozzle as claimed in claim 10 including a non return valve disposed intermediate the chamber and the inlet, saidnon return valve being disposed to close to prevent fuel flowing from the chamber when the supply of fuel ceases, a restricted passage being provided to by-pass the non return valve to allow fuel to flow from the chamber at a restricted rate.

12. A fuel injection nozzle as claimed in claim 11 in which the degree of restriction offered by the restricted orifice is variable in accordance with the volume of fuel stored in the chamber.

the groove on said one cylindrical member is profiled to constitute a variable throttle.

15. A fuel injection nozzle as claimed in claim 14 including a restrictor disposed between the chamber and the inlet.

l I I I 

1. A fuel injection nozzle of the kind comprising a nozzle head, a supply orifice formed in the nozzle head and through which fuel flows to a combustion space of an internal combustion engine, a bore formed in the head, said bore at one end thereof communicating with said orifice, a seating defined at said end of the bore, a valve member slidable within said bore and shaped for co-operation with said seating to prevenT fuel flow through said orifice, resilient means for urging the valve member into contact with the seating, a a fuel inlet, passage means through which fuel under pressure from the inlet can be applied to said valve member to lift the valve member from the seating against the action of the resilient means to permit fuel flow through the orifice, means disposed intermediate the valve member and the resilient means, said means defining a variable volume chamber to which fuel is supplied from said inlet, means for limiting the maximum volume of the chamber, a restricted orifice through which fuel flows to said chamber from the inlet, the arrangement being such that fuel flowing through the inlet into the chamber flows at a restricted rate through the restricted orifice so that the pressure within the chamber is lower than that applied to the valve member, said fuel acting to increase the volume of the chamber by movement of the means disposed between the valve member and the resilient means against the action of the resilient means, said valve member because of the differing pressures applied thereto lifting slightly from the seating to allow restricted flow of fuel through said supply orifice, and when said chamber has attained its maximum volume the valve member being lifted completely from the seating to allow substantially unrestricted flow through the supply orifice.
 2. A fuel injection nozzle as claimed in claim 1 in which the means for limiting the maximum volume of the chamber comprises a valve operable to cut off the supply of fuel to the chamber.
 3. A fuel injection nozzle as claimed in claim 2 including a groove formed on the means disposed between the valve member and resilient means, said groove communicating with said chamber, and a port formed in the wall of the cylinder in which the piston member is located, said port communicating with said inlet by way of the restricted orifice, the arrangement being that when the piston member has moved a predetermined distance the groove will move out of register with the port and the volume of the chamber will be limited.
 4. A fuel injection nozzle as claimed in claim 3 including a non return valve through which said groove communicates with the inlet, said non return valve opening when the supply of fuel through the inlet ceases, to permit fuel to escape from said chamber.
 5. A fuel injection nozzle as claimed in claim 4 in which the degree of restriction offered by said restricted orifice is made to increase as the speed of operation of the associated engine increases.
 6. A fuel injection nozzle as claimed in claim 2 in which said means disposed between the valve member and resilient means comprises a piston member and a distance piece disposed between the piston member and valve member, the chamber being defined between the piston member and distance piece and a port formed in the wall of the bore in which the piston member is located, said port being opened to the chamber when the piston member has moved a predetermined amount, and the port communicating with one end of a cylinder containing a spring loaded valve element, the port when opened allowing fuel under pressure to be applied to said valve element to move it against the action of its spring, the valve element when so moved, cutting off the supply of fuel from the inlet to the chamber.
 7. A fuel injection nozzle as claimed in claim 6 in which the valve element is provided with a restricted opening and through which fuel can flow to a drain from said chamber when the supply of fuel under pressure ceases.
 8. A fuel injection nozzle of the kind comprising a nozzle head, a supply orifice formed in the nozzle head and through which fuel flows to a combustion space of an internal combustion engine, a bore formed in the head, said bore at one end thereof communicating with said orifice, a seating defined at said end of the bore, a valve member slidable within said bore and shaped for co-operation with said seating to prevent fuel flow throuGh said orifice, resilient means for urging the valve member into contact with the seating, a fuel inlet, passage means through which fuel under pressure from the inlet can be applied to said valve member to lift the valve member from the seating against the action of the resilient means to permit fuel flow through the orifice, a pair of cylindrical members, disposed intermediate the valve member and the resilient means, a chamber being defined between the cylindrical members, and the chamber being in constant communication with the inlet, a restricted orifice through which fuel flows to said supply orifice at a restricted rate, and a by-pass passage through which fuel can flow to said supply orifice at a substantially unrestricted rate when the chamber has attained its maximum volume.
 9. A fuel injection nozzle as claimed in claim 8 including a stop to limit the extent of movement of the one cylindrical member adjacent the resilient means against the action of the resilient means.
 10. A fuel injection nozzle as claimed in claim 9 in which said by-pass passage is controlled by said one cylindrical member, said member having a groove formed thereon and which registers with a pair of ports to complete said by-pass passage.
 11. A fuel injection nozzle as claimed in claim 10 including a non return valve disposed intermediate the chamber and the inlet, said non return valve being disposed to close to prevent fuel flowing from the chamber when the supply of fuel ceases, a restricted passage being provided to by-pass the non return valve to allow fuel to flow from the chamber at a restricted rate.
 12. A fuel injection nozzle as claimed in claim 11 in which the degree of restriction offered by the restricted orifice is variable in accordance with the volume of fuel stored in the chamber.
 13. A fuel injection nozzle as claimed in claim 11 in which the degree of restriction offered by the restricted orifice is variable in accordance with the pressure drop across the orifice.
 14. A fuel injection nozzle as claimed in claim 12 in which the groove on said one cylindrical member is profiled to constitute a variable throttle.
 15. A fuel injection nozzle as claimed in claim 14 including a restrictor disposed between the chamber and the inlet. 